According to the prior art, automatic transmissions, particularly for motor vehicles, comprise planetary gear sets that are shifted using friction elements or shift elements such as clutches and brakes, and typically are connected to a start-up element, such as a hydrodynamic torque converter or a fluid coupling, that is subject to a slip effect and is provided optionally with a lock-up clutch.
Such automatic transmissions have been described numerous times in the prior art and are continually undergoing further development and improvement. These transmissions should have a sufficient number of forward gears as well as at least one reverse gear, and a suitable transmission ratio which is highly favourable for motor vehicles with a high overall gear ratio as well as a favourable gear interval. Furthermore, they should enable a high startup transmission ratio in the forward direction and contain a direct gear. In addition, an automatic transmission should require moderate complexity and few shift elements, wherein only one shift element is engaged and one shift element is disengaged during sequential shifting.
Such an automatic transmission is known, for example, from DE 199 12 480 B4 by the applicant. It comprises three single-carrier planetary gear sets, as well as three brakes and two clutches for shifting six forward gears and one reverse gear, a input shaft and an output shaft, wherein the carrier for the first planetary gear set is continuously connected to the ring gear of the second planetary gear set, and the carrier for the second planetary gear set is continuously connected to the ring gear of the third planetary gear set, and the input shaft is directly connected to the sun gear of the second planetary gear set.
Furthermore, in the known transmission, the input shaft is connectable by means of the first clutch to the sun gear of the first planetary gear set, and by means of the second clutch to the carrier of the first planetary set, wherein the sun gear of the first planetary gear set is connectable by means of the first brake to a housing of the transmission, and the carrier of the first planetary gear set is connectable by means of the second brake to the housing of the transmission, wherein the sun gear of the third planetary gear set is connectable by means of the third brake to the housing of the transmission. The input shaft of the transmission is continuously connected to the carrier for the third planetary gear set and the ring gear of the first planetary gear set.